Method and apparatus for capping containers of unstable dimensions



Sept. 17, 1968 A. J. GARVIN 3,401,498

METEOD AND APPARATUS FOR CAPPING CONTAINERS OF UNSTABLE DIMENSIONS FiledSept. 50, 1965 2 Sheets-Sheet 1 Inventor ALEX JAMES GARVIN Sept. 17,1968 A. J. GARVIN 3,401,498

METHOD AND APPARATUS FOR CAPPING CONTAINERS OF UNSTABLE DIMENSIONS FiledSept. 30, 1965 2 Sheets-Sheet 2 Inventor ALEX JAMES GARVIN} UnitedStates Patent ABSTRACT OF THE DISCLOSURE Method and apparatus forcapping tubular containers of flexibleconstitution by holding thecontainer with one end exposed and applying a moldable film closuresheet over the exposed end of the container while flexing the latterinwardly. The film closure is applied to the container by application ofheat and pressure on the closure in a mold recess, and the container isreleased which renders the film closure taut.

' The invention relates to a method of capping containers of unstabledimensions such as cylindrical tubular cardboard containers and thelike, and apparatus therefor.

' The capping or closing of containers'and packages utilizing automatictechniques is generally desirable for cost reduction purposes,particularly where such packages are of small unit size, for examplevending machine packages. Furthermore, in his type of application it isessential that each package should conform as nearly as possible to astandard dimension and design in order to reduce rejects and to minimizefeed failure in thevending' machines. While some of these problems mayhave been overcome to a greater or lesser degree in particular.instances of prior package designone of the principalfactors limitingcap and closure techniques has been the variation or lack of stabilityin the dimensions of apparentlyunifo rm containers due to variation inmoisture content for example and other similar conditions, render- ,ingthe application of improved capping methods'a difiicult problem. Thus inprior packaging design the capping methods applied to a low costpackages of this type have caused a variety of problems such as thecreation of a bulky or uneven and closure or cap rendering it diflicultto achieve reliable' feeding in J a vending machine for example. Othersuch methods have involved an unacceptable number of operations,including handling, increasing v the cost thereof. Further disadvantageshave included poor sealing leading to deterioration and loss of thecontents of the package, difliculty inopening the cap to obtain accessto the contents, and other like problems have been exhibited in variouscircumstances. I

Accordingly it is an objective of this invention to provide a method ofcapping containers of unstable dimensions which is efiicient andreliable in use and which is economic and simple in operation and whichresults in a reliable container cap of a uniform, inconspicuous,

design.

More particularly it is an object of this invention to provide a methodhaving the foregoing advantages which is particularly adapted to highspeed automatic operation.

3,401,498 Patented Sept. 17, 1968 More particularly it is an object ofthis invention to provide a method having the foregoing advantages whichis suitable for use with containers of cylindrical tubular cardboardmaterial. i

It is a further objective of the invention to provid apparatus forcapping containers of unstable dimensions according to the said method.

The invention seeks to achieve the foregoing and other objectives whichwill become apparent from the following description of a preferredembodiment of the invention by the provision of a method of cappingcylindrical tubular containers of unstable dimensions and comprising;applying a moldable film closure sheet over an end of said containerwith a portion thereof overlapping said container around said end;tensioning said closure sheet; applying heat and pressure to saidoverlapping portion of said closure sheet while maintaining said tensionprogressively folding the same around said end of said container andmolding the same to adopt and conform to the contour of said containeradjacent said end and to bond the same thereto forming a good liquidtight seal therewith; and subsequently permitting same to cool.

A preferred embodiment of the invention will now be described by way ofexample only with reference to the following drawings in which likereference devices refer to like parts thereof throughout the variousviews and diagrams and in which;

FIGURE 1 is a schematic illustration showing the location of the stagesat which the instant capping method may be performed in a continous flowproduction line;

FIGURE 2 is an enlarged cross-sectional view of the apparatus forperforming the capping operation according to the invention at aninitial stage in its cycle;

FIGURE 3 is an enlarged cross-sectional view corresponding to that ofFIGURE 2 with the apparatus shown in a position corresponding to a finalstage in its cycle;

FIGURES 4 and 5 are greatly enlarged detail views of those memberswithin the phantomed area A of FIGURE 3 showing two intermediate stagesin the cycle of operations of the method according to the invention.

The illustration of FIGURE 1 discloses the general features of a flowproduction line for the manufacture of cylindrical tubular vendingpackages filled with any suitable wares such as powdered soap or othercomminuted.

material.

In FIGURE 1 tubular containers 10 are supported intermediate their endsby clamps 11 movably mounted on belt 12 carrying containers 10 inintermittent motion. A first capping station 13 is provided beneath belt12 for applying a lower cap 14 to container 10 and a second cappingstation 15, of similar design to station 13, is provided above belt 12at a distance from station 13 for applying an upper cap 16 to container10. Intermediate capping stations 13 and 15 the filling station 17 isprovided which includes a hopper 18 for containing a supply ofcomminuted material for example, which is communicated to individualcontainers 10 by means of flexible conduit 19 engageable sequentiallywith each said container 10 as the same is moved by belt 12. Bin 20 isprovided for collection of the completed vending packages 21 whenreleased by clamps 11 by means (not shown). Since the operation of bothcapping stations 13 and 15 is the same station 15 is now described indetail it being understood that station 13 performs the same function inan opposed direction.

From FIGURES 2 and 3 capping station 15 will be seen to comprise moldmember 22 provided with mold recess 23 for reception of an end of acontainer 10 therein. Recess 23 is lined with synthetic liner wall 24formed, in this preferred embodiment of heat-stable plastic material ofany suitable type, and of a thickness insufficient to deteriously affecttransfer of heat therethrough, shaped to provide a generallyfrusto-conical profile.

Bolts 25 engage either side of mold member 22 and provide aquick-release attachment securing the same to heating plate 26 forheating of mold member 22. Plate 26 is itself heated by electricalelement 27 and is provided with temperature gauge 28 for control.Heating plate 26 is itself supported by backing plate 29 both of whichare fastened to the end of shaft 30 by stud 31. Shaft 30 is reciprocatedaxially by any suitable power transmission means shown generally as 32(see FIGURE 1). Cap forming material 33 of moldable, thermoplastic sheetstock is wound on drums 34 (see FIGURE 1) for storage and windingrespectively, which are omitted from FIG- URES 2 and 3 for clarity,driven by any suitable winding mechanism (not shown) to procureintermittent movement thereof in timed relation to the reciprocalmovement of shaft 30. In order to cut a disc of material 33 for formingan individual cap 16 cutting die 35 is formed on the lower surface ofmold member 22 being provided with an internal shoulder 36 for retainingthe cut disc of material 33 in predetermined location therein. In thispreferred embodiment shoulder 36 is formed by an integral portion ofliner Wall 24 to redue friction thereon. Material 33 is supported duringcutting on a suitable cutting bed provided by plate 37 movably mountedon bolts 38 and urged upwardly by springs 39. In order to reducefriction and extend the life of cutting die 35 plate 37 is provided withwearing surface plate 40 formed of the same plastic as liner wall 24.Opening 41 is provided in plate 40 just large enough to permit the endof container 10 to pass therethrough but of lesser diameter than cuttingdie 35 to retain the disc of material 33 therewithin. Material 33 isclamped on plate 37 during cutting by means of clamps 42 formed ofplastic material to reduce friction with material 33, clamps 42 beingreciprocated vertically by any suitable mechanism (not shown) in timedrelation with the movement of mold member 22.

In order to support container 10 during the capping operation supportplate 43 is provided for the purpose, movably mounted on bolts 44 andurged upwardly by springs 45 thus permitting container 10 to movedownwardly when the pressure of mold member 22 exceeds the upward forceof springs 45.

The specific capping method according to this preferred embodiment ofthe invention comprises the following steps: A container 10 filled withmaterial 33 is moved by clamps 11 into station 15 with its central axisdirectly in alignment with the axis of movement of mold member 22 andwith its lower end resting on plate 43 the members being substantiallyin the position shown in FIGURE 2 at this point. Mold member 22 thenbegins its downward stroke under the influence of power transmission 32and immediately die 35 is brought into contact with plastic cappingmaterial 33 and cuts out a disc thereof against surface plate 40 andthen continues downwardly forcing plate 37 downwardly against springs39, with opening 41 in plate 40 passing over the upper end of container10.

The downward movement of die 35 carries with it the disc of material 33located therewithin and sandwiched between shoulder 36 and surface plate40. It will be noted that the disc of material 33 is of larger diameterthan container 10 and that an annular portion thereof will overlap thesides of container 10, such portion corresponding substantially to thearea thereof sandwiched as aforesaid. The disc of material 33 is thusbrought into contact with the upper end of container 10 and with thecentre thereof in alignment with the axis of container 10 and completelyclosing the same.

Continued downward movement of die 35 around container 10 causes thedisc of material to become tensioned and stretched and such tensioningwill increase as the annular portion of material 33 is drawn out ofengagement with shoulder 36 and surface plate 40. By this stage in thecycle liner wall 24 will begin to engage container 10 squeezing material33 therebetween and folding the annular portion thereof around container10 and increasing the tensioning therein, the position of the membersbeing substantially as shown in FIGURE 4. At the same time heat fromelement 27 will pass through mold member 22 and liner wall 24 intomaterial 33 causing a limited plastic flow thereof and permitting thesame to become molded smoothly around container 10 adopting andconforming to the contour thereof, any tendency for wrinkles or folds tooccur therein being overcome by the flowing of the plastic into the newshape.

Com letion of the downward movement will bring liner wall 24 furtherdown over container 10, which due to the frusto-conical configurationthereof will increasingly constrict the upper end thereof which isunsupported against such pressure. The progressive build-up of pressureon container 10 will eventually overcome the upward bias of springs 45and plate 43 will move downwardly thus limiting the pressure oncontainer 10 to predetermined point below the point at which damagewould be caused to container 10 or material 33. During this period themembers will pass through the position shown in FIGURE 5 terminating inthe position shown in FIG- URE 3. The precise relation of liner wall 24and container 10 will depend principally upon the diameter of container10 causing either greater or lesser penetration therein. Inasmuch as acontainer 10 of cardboard may vary 2% or more in diameter and in lengthdue to changes in moisture content for example, FIGURE 3 can only betaken as as approximate position since both the penetration and themovement of plate 43 will be subject to variation.

It will be understood that the shaping and dimensions of the liner wall24 are closely related to and determined by reference to the diameter ofthe container 10 and the maximum variation in diameter encounteredbetween different containers.

In the particular example shown the inclination of the walls from thetrue cylinder is about 2 and in any case should not be less than about 1or greater than about 4 so as to ensure satisfactory molding of theplastic film in the plane of the containers walls. The diameter of thetubular containers is in the region of one and onehalf inches and thedepth of the tapered section of the mold is just under an inch.Obviously the taper of the mold must be in excess of the greatestvariation of diameter d of the container in this case about .015 of aninch and should therefore be not less than about 2% of the diameter dwhere the diameter d is liable to a variation of 1% so that the mold isgiven a taper of approximately one sixteenth of an inch which therebydetermines its depth.

Thus the relationship may be summarized that given a diameter d of thecontainer and a variation in d between containers of up to d/ then themold should taper about d/50 and have a wall inclination of an angle xof between 1 and 4". Where the maximum variation between containers issome other fraction 1'' of d then the mold should taper more than f butretain the same wall angle x thereby determining the required depth ofthe mold recess.

On completion of the downward stroke a momentary dwell period may beutilized to ensure complete penetration of heat through material 33,particularly where, for example, container 10 is coated with a likeplastic material and it is required to procure a bond therewith by heatsealing thereof.

Thereafter power transmission 32 raisesmoldmember 2 2 upwardly drawingliner wall 24 away from container 10 which is still' held by clamps atthis point. Material 33 will then cool and set rapidly and cap 16 iscompleted. Removal of liner wall 24 from container 10 will releasecontainer 10 from constriction and permit the same to flex outwardly toa limited extent thus increasing the tension in-cap 16. As mold member22, reaches its upper position once more clamps 42 are momentarilyreleased and drums 34 rotate moving a fresh piece of material 33 beneathdie 35 for cutting thereof on the next cycle of operation. 4

Simultaneously with the. movement of material 33 belt 12 will moveclamps 11 thus removing the completed package 21 and moving a newcontainer 10 into registration with mold member 22.

It will be noted that the above operation will accommodate relativelysubstantial variations in the size of container 10 without loss ofefliciency or economy, even where such variations occur at randomintervals. Furthermore the caps 14 and 16 resulting from the said methodeffect an eflicient liquid and airtight sealing of container 10 whilealso forming integral end closures for container 10 forming the sameinto the complete package 21 thus economizing in container material andalso providing for easy opening thereof by merely puncturing a cap 14 or16. .The utility of the package 21 is also increased by the smooth,wrinkle-free exterior surface of caps 14 and 16 which permits the use ofsuch packages in vending machines, with a minimum of servicing.

This application is a continuation-in-part of my copending applicationSer. No. 229,898 filed Oct. 11, 1962 for Method and Apparatus forCapping Containers of Unstable Dimensions.

The foregoing is a description of a preferred embodiment of theinvention by way of example only and the invention is not limited to thespecific features shown but contemplates all such variations as comewithin the spirit of the invention as defined by the following claims.

What I claim is:

1. The method of capping cylindrical tubular containers of unstabledimensions unsupported at at least one end thereof and permittinglimited flexibility and comprising: applying a moldable film closuresheet over an end of said container with a portion thereof overlappingsaid container around said end; applying heat and pressure to saidoverlapping portion of said closure sheet in an area of said containerunsupported against said pressure around said end thereof, said pressurecausing deformation and constriction of said container in said area;progressively continuing said heat and pressure to mold said overlappingportion of said sheet and cause it to adopt and conform to the contourof said container in said area and to bond the same thereto forming agood liquid tight seal therewith; and subsequently removing said heatand pressure and permitting said area of said container to flexoutwardly and tension said sheet across said end.

2. The method of capping cylindrical tubular containers of unstabledimensions unsupported at at least one end thereof and permittinglimited flexibility and comprising: cutting a disc of thermoplasticcapping sheet material of a diameter in excess of the maximum diameterof said container; registering said disc in alignment with the axis ofsaid container and in contact with an end thereof, the circumference ofsaid disc defining an annular overlapping portion therearound; causingaxial movement of said end of said container relative to a mold memberof generally frusto-conical shape fitting progressively closer aroundsaid end of said containers and pressing said overlapping annularportion of said disc into close contact with said container over andaround said end; said pressure causing limited inward flexing of saidend; terminating said relative axial movement when said pressure reachesa predetermined maximum value for said container below that suflicientto damage said end of said container; simultaneously applying heat tosaid overlappingportion of said disc causing the sameto flow and adoptthe contour of said end of said container and form a good liquid tightseal therewith; and subsequently withdrawing said container from saidmold member. v 3. Apparatus for capping containers of unstabledimensions and comprising: container support means operable to move saidcontainer sequentially into and out of a capping station; means forsupporting moldable thermoplastic capping sheet material movably locatedin registration with an open end of a said container in said station;sheet cutting means operable to cut a portion of said sheet, the shapeofsaid cut portion being similar to that of said open end and large enoughto overlap a portion of said container therearound; molding meansdefining a mold recess of frusto-conical shape tapering inwardly from anopen mouth to accommodate containers of varying dimensions and operableto apply heat and pressure to said out portion of said sheet and saidcontainer to form the same into a cap around said open end of saidcontainer; and pressure regulating means for controlling the pressureapplied to said sheet and said container during forming as aforesaid.

4. Apparatus for capping containers of unstable dimension as claimed inclaim 5 wherein said container is of cylindrical shape having an averagediameter of d and including stop means within said sheet cutting meansretaining said cut portion of said sheet therewithin, and beingdimensioned and oriented to fit around said open end of said containerand permit the same to pass therethrough; and wherein said mold recesstapers inwardly at an angle of between about 1 degree and 4 degrees, andpreferably about 2 degrees and wherein the minimum diameter and maximumdiameter of said mold recess vary by between about 2 percent and 4percent and an intermediate diameter of d.

5. Apparatus for capping containers of unstable dimensions as claimed inclaim 5 wherein said container is of cylindrical shape having an averagediameter of d and including a bed portion supporting said sheet materialin registration with said die member for cutting as aforesaid and havingan opening therein sufiicient for said container end to passtherethrough; and wherein said mold recess tapers inwardly at an angleof between about 1 degree and 4 degrees, and preferably about 2 degreesand wherein the minimum diameter and maximum diameter of said moldrecess vary by between about 2 percent and 4 percent and an intermediatediameter of d.

6. Apparatus for capping containers of unstable dimensions as claimed inclaim 3 wherein said container is of cylindrical shape having an averagediameter of d and including clamping means operable to momentarilyengage and clamp said sheet during cutting as aforesaid; and whereinsaid mold recess tapers inwardly at an angle of between about 1 degreeand 4 degrees, and preferably about 2 degrees and wherein the minimumdiameter and maximum diameter of said mold recess vary by between about2 percent and 4 percent and an intermediate diameter of d. I

7. Apparatus for capping containers of unstable dimensions as claimed inclaim 3 wherein said container is of cylindrical shape having an averagediameter of d and including said molding means having a mold recessdefined by interior wall portions dimensioned and oriented to fit overand closely engage said container around its said open end and being offrusto-conical shape tapering inwardly from an open mouth to accommodatecontainers of varying dimensions and wherein said mold recess tapersinwardly at an angle of between about 1 degree and 4 degrees, andpreferably about 2 degrees and wherein the minimum diameter and maximumdiameter of said mold recess vary by between about 2 percent and 4percent and an intermediate diameter of d.

8. Apparatus for capping containers of unstable dimensions as claimed inclaim 3 wherein said container is of cylindrical shape having an averagediameter of d and wherein said mold recess tapers inwardly at an angleof between about 1 degree and 4 degrees, and preferably about 2 degreesand wherein the minimum diameter and maximum diameter of said moldrecess vary by between about 2 percent and 4 percent and an intermediatediameter of d; pressure means operable to force said mold member towardssaid container with said recess over said open end of said container,said interior Wall portions applying pressure to said cut portion ofsaid sheet and said forming the same and simultaneously progressivelyconstricting said open end of said container therearound; and means forheating said mold member to a predetermined s" temperature rangesufiicient to cause said sheet material to flow and bond with saidcontainer during the application of pressure thereto as aforesaid.

ReferencesCited I UNITED STATES-PATENTS 2,075,727 3/1937 Karlsson 'etall. 53--297 2,263,152 11/1941 Wilcox 5339 X 10 WILLIAM w. DYER, In,Primary Examiner.

R. L. FARRIS, Assistant Examiner.

